SAP Note 26926 - ME25 Copy PReq then source determination

Symptom:

Transaction ME25 (create purchase order vendor unknown): If you copy a PReq as a reference, transfer the item(s) using transfer + detail and allocate a source of supply on the detail screen, the source of supply fields remain empty (contract number, info record number, etc.), except for the name of the vendor.

Cause and prerequisites

Program error

Solution
Corrected in Release 3.0B. You can implement a preliminary correction by inserting the lines indicated below in the specified program: